Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N9/00—Electrical control of exhaust gas treating apparatus
  • F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
  • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
  • F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
  • F01N3/0885—Regeneration of deteriorated absorbents or adsorbents, e.g. desulfurization of NOx traps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N9/00—Electrical control of exhaust gas treating apparatus
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/021—Introducing corrections for particular conditions exterior to the engine
  • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
  • F02D41/024—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
  • F02D41/0245—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus by increasing temperature of the exhaust gas leaving the engine
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
  • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
  • F02D41/1446—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being exhaust temperatures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
  • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
  • F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
  • F02M26/23—Layout, e.g. schematics
  • F02M26/25—Layout, e.g. schematics with coolers having bypasses
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2250/00—Combinations of different methods of purification
  • F01N2250/14—Combinations of different methods of purification absorption or adsorption, and filtering
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2430/00—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
  • F01N2430/06—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics by varying fuel-air ratio, e.g. by enriching fuel-air mixture
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
  • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
  • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
  • F01N3/025—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust
  • F01N3/0253—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust adding fuel to exhaust gases
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1433—Introducing closed-loop corrections characterised by the control or regulation method using a model or simulation of the system
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
  • F02M26/02—EGR systems specially adapted for supercharged engines
  • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
  • F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/12—Improving ICE efficiencies
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/40—Engine management systems

Definitions

• the subject of the invention is a method and a device for controlling the temperature of the exhaust gases of a heat engine, in particular during the regeneration phases of the post-treatment system.
• the pollutants are trapped and stored during normal engine operation and are periodically treated, during regeneration phases that require a specific combustion mode to ensure the thermal levels and / or fuel richness required.
• the fuel injection rate in the combustion chambers of the cylinders can be adjusted according to the needs so as to operate according to a more or less rich combustion mode and the result is a variation in the temperature of the gases. exhaust and the proportion of oxidants and reducers in these gases.
• the flow rate and the temperature of the exhaust gas also depend, at each instant, on the engine speed controlled by the driver as a function of the traffic conditions.
• a catalyst having a means of cleaning is usually available in the purification system.
• accumulation of nitrogen oxides called "NO x -Trap" which is integrated in the exhaust line and in which are trapped nitrogen oxides emitted during normal operation of the engine.
• Nitrogen oxide storage is described in detail, for example, in EP-A-0580389.
• Such a catalyst is regenerated periodically by exploiting the engine in a rich regime for a certain time in order to decompose the nitrates by releasing NO x, which is then reduced to nitrogen by the reducing agents such as H 2 , HC, and CO contained in the gases. exhaust, as described in the document cited above.
• the post-treatment system normally comprises a particulate filter, for example catalytic, whose inner wall is covered with a layer of a material impregnated with precious metals, called “Wash Coat", providing an oxidation function intended to reduce the combustion temperature of the soot particles.
• a particulate filter for example catalytic
• Wash Coat a material impregnated with precious metals
• the temporal characteristics of the response of such a process to the control step limit the performance of a feedback control in terms of setpoint tracking and it may be impossible to avoid overruns. the maximum permissible temperature.
• the process because of the sensitivity of the process to changes in operating conditions, it will be very difficult to achieve a fairly stable control over the entire operating field of the engine without determining its parameters for each of the operating conditions. is inadmissible in terms of memory space dedicated to this function.
• the invention relates to a new control method for regulating the internal thermal of the catalyst without depending on the conditions of observation of the state of the system for the development of the appropriate control.
• the invention makes it possible to adapt optimally to the particular conditions of trapping and elimination of the various pollutants that may be contained in the exhaust gas.
• the invention therefore relates to a method for controlling the temperature of the gases in an exhaust circuit of a heat engine fed with a mixture whose proportion of fuel can be adjusted according to a combustion mode plus or less rich, said exhaust circuit comprising at least one post-processing member in which is trapped and stored at least one pollutant contained in the exhaust gas, this post-treatment member being subjected periodically to regeneration phases by raising the temperature of the exhaust gas to a set temperature, during a regeneration time allowing the removal of stored pollutants.
• the time of each regeneration phase is divided into a succession of fractional periods of adjustment of the motor, alternatively in two combustion modes with different richness, respectively a warmer mode for which the input thermal power supplied by the gases is greater than a desired setpoint power to obtain the setpoint temperature and a less hot mode for which the incoming thermal power is lower than the target power, the duration of each fractional period being controlled so that the surplus of energy brought in a period in warmer mode, is compensated by the energy failure in the next period in less hot mode and vice versa, to maintain the temperature of the gas at the outlet of the post-treatment member, in the vicinity of an average temperature corresponding to the set temperature.
• the duration of each fractional period in the warmer mode or in the warmer mode is determined so that the surplus or the energy deficiency brought by the gases during said period, relative to the nominal power, does not exceed does not exceed a given limit.
• the proportions of fuel in the warmer mode and in the warmer mode and the respective durations of the fractional periods are determined so that the amplitude of variation of the temperature of the gases, in the post-processing unit, relative to the setpoint temperature and / or the difference between the power entering the post-processing unit and the target power, do not exceed the same limit, in excess in warmer mode and by default in cooler mode .
• the durations of the fractional periods, respectively in the warmer mode and in the warmer mode are determined so that the energy supplied in each period, corresponding to the difference between the thermal power W 6 entering the post-processing unit and the nominal power W c , does not exceed, by excess or by default, the same limit E max given by the equation:
• T s is the set temperature expected during the regeneration phase
• M is the mass of the post-treatment organ
• C m is the heat capacity of the post-treatment unit
• ⁇ is the proportion, with respect to its total length, of the post-treatment unit between the exhaust gas inlet zone and the zone where the temperature reaches its maximum level T max .
• the surplus or the lack of energy supplied by the gases during a period is calculated, at each moment, by integration as a function of time of the difference between the reference power and the power entering into the room. post-treatment organ.
• the desired power W c necessary to obtain the set temperature Ts at the output of the
• Post-treatment is equal to the sum of the theoretical power W s at the output of the post-processing unit and losses W p , said theoretical power W s being given by the formula:
• Ts T s * Q ech * C p in which Ts is the set temperature necessary for the regeneration, 15 C ec h the flow of the exhaust gas which can vary according to the engine speed and C p the heat capacity of the gases exhaust depending on their composition that may vary depending on the mode of combustion.
• the thermal power W 6 entering the posttreatment member at each instant can be given by the formula * O ⁇ ec uH, C * ⁇ p + + WWeXO wherein Te is the temperature of the gases measured at each moment upstream of the post-processing unit, Q ech the flow of exhaust gas C p capacity heat and W exo the thermal power provided by the oxidizing and reducing masses that react in the post-treatment organ.
• Figure 1 is a general diagram of the intake and exhaust circuits of a combustion chamber of an internal combustion engine.
• FIG. 2 is a diagram of an exhaust system equipped with an exhaust gas aftertreatment system.
• FIG. 3 is a diagram showing an example of variation, during a regeneration phase, of the flow rate of the exhaust gases according to the engine speed and the corresponding variation of the necessary reference power and of the
• Figure 4 is a general diagram illustrating the method according to the invention.
• Figure 5 is a diagram of a temperature control system for implementing the method.
• FIG. 1 diagrammatically shows a combustion chamber 10 of a motor supplied with fuel by an injector January 1 and connected to circuits 1 for air admission and 2 for exhausting the combustion gases.
• the air intake circuit 1 comprises a compressor 14 driven by a turbine 13 placed on the exhaust circuit 2 which can, in addition, supply a circuit 12 for recycling a portion of the gases in the engine.
• the various circuits may include various ancillary organs such as exchangers for heating air or cooling of recycled gases, solenoid valves for flow control, sensors, etc.
• an output circuit 20 which, to reduce pollution, comprises at least one post-processing member 21.
• This post-treatment unit usually of the NO x -Trap type, makes it possible to retain and store the nitrogen oxides contained in the exhaust gas and is usually associated with a particulate filter 22 which retains, in the form of soot, the particles contained in the gases.
• the exhaust circuit 2 of an internal combustion engine 10 usually comprises, downstream of the turbine 13, a first post-treatment member 21 of the oxidation catalyst type and a second member 22 such as a particulate filter, the gases thus cleaned up being discharged into the atmosphere by a discharge circuit 23.
• a discharge circuit 23 Often, an additional injector is placed in the exhaust circuit 2.
• the pollutants accumulated during normal operation in the post-treatment unit 21 are eliminated in regeneration phases, generally by raising the temperature of the gases with engine control, respectively in a rich mixture for the desorption of the sulfur in the posttreatment member 21 and lean mixture for the combustion of soot in the particulate filter 22.
• the injector 1 1 or the additional injector placed in the exhaust is controlled, usually by a unit control receiving the information transmitted by various sensors and associated with a model that periodically controls the transition to the regeneration phase and the maintenance of the desired setpoint temperature.
• the temperature T 6 and the flow rate Q eCh of the exhaust gases measured, for example, by sensors 31 placed upstream or downstream of the turbine 13, vary at each instant as a function of the engine speed controlled by the driver. .
• curve 3 shows the possible evolution, over time, of the exhaust gas flow rate, which varies according to the engine demand, that is to say from the position of the acceleration pedal and gearbox ratios during the relevant period.
• the composition of the exhaust gas is also known and it is therefore possible to deduce therefrom their heat capacity C p at the moment considered.
• the exhaust gases leaving via the pipe 20 have the same flow rate Q eCh and their temperature T s , which can be measured by a sensor 15, corresponds to the internal temperature of the catalyst 21.
• the problem of the invention is therefore to maintain this temperature T s , throughout the duration of a regeneration phase, in the vicinity of a set temperature for which the operation of the catalyst is optimal but which must not be exceeded to avoid deterioration of the catalyst.
• C p is the heat capacity of the gases which depends on their composition, that is to say the combustion mode, more or less rich, imposed on the engine at this time.
• the principle of thermal management is to provide in the catalyst 21 an average input thermal power substantially equal to the outgoing thermal power, that is to say, the power discharged to the desired set temperature.
• This incoming thermal power consists, on the one hand, of the thermal power supplied directly by the heat of the gases because of their temperature Te and their flow Q eCh and, on the other hand, of the potential power provided indirectly by the exothermic reaction capacity of the masses oxygen or reductants present in the exhaust gas and which react partially or completely in the catalyst.
• This exothermic reaction provides, in fact, additional energy W exo which, in the catalyst, adds to the direct heating power of the gases to raise their temperature.
• the incoming power W 6 expressed in J / s, can therefore be written:
• This input thermal power can therefore be calculated from a measurement, an estimation or the modeling of the temperature T 6 and the flow rate Q eCh of the gases in the pipe 20, at the inlet of the catalyst 21, as well as of their composition, in particular oxygen or reducing emissions, which make it possible to determine their heat capacity C p and the potential power of exothermic reaction W exo .
• curve 3 gives an example of a possible evolution, over a period of time, of the flow of the exhaust gas Q eCh for obtaining an outlet temperature T s , this flow varying in a certain way according to the regime requested to the engine.
• the thermal power that must be provided by the gases at this temperature to obtain a substantially constant output temperature T s evolves in the same way as the gas flow rate as a function of the engine speed, but it also depends on the richness of the mixture according to the mode of combustion chosen, as well as losses.
• Curve 30 indicates the evolution of the nominal power W c theoretically necessary in view of the losses, in order to obtain the target temperature at the outlet of the catalyst. It is, however, difficult to adjust the operation of the engine during the regeneration time to provide, at any time, the power necessary to obtain and maintain the set temperature.
• the idea of the invention is to control an alternation of rich and poor phases by combining them, so as to provide either an excess of energy through a richer mode of combustion (R) and, consequently, hotter than necessary, a defect of energy by a mode of poorer combustion (P) and, consequently, less hot than necessary, this excess and this defect of energy being able to be compensated so as to maintain the temperature, in the catalyst, to an average value corresponding to the set temperature.
• R richer mode of combustion
• P mode of poorer combustion
• the two curves 31, 32 are substantially parallel and shifted from side to side. other of the curve 30 corresponding to the power theoretically required W c to obtain and maintain the set temperature.
• the mode change makes it possible to obtain, in hot mode (R), a surplus of energy S with respect to the power theoretically necessary, or, in cold mode (P), a defect of D. energy
• Figure 4 is a general diagram illustrating the successive steps of such a method.
• the curve 3 indicates, on the ordinate, the evolution of the exhaust gas flow rate, which can vary according to the orders given by the driver of the vehicle during a regeneration time indicated on the abscissa and whose duration, according to the regeneration method, can range, for example, from a few tens of seconds to several minutes.
• the curve 30 indicates, as in FIG. 3, the theoretical power W c that should be provided by the gases for maintaining, at the outlet of the catalyst, a constant temperature Ts.
• the reference power W c varies in a similar way to the flow rate.
• the fuel injection will be modified alternately to go from a richer combustion mode than necessary to a less rich combustion mode.
• the resulting thermal powers at the inlet of the catalyst are indicated, as in FIG. 3, by the curve 31 for the warmer mode (R) and by the curve 32 for the less hot mode (P).
• the fuel injection can be set in each of the two modes, respectively hot and cold, so that, at a given moment, and according to the combustion mode chosen and the engine speed, the surplus power S brought in hot mode compared to the power W c theoretically necessary, of the same order, in absolute value, as the power failure D resulting at the same time, the cold mode operation. Therefore, at a time ti, the two points ⁇ i on the curve 31 and éi on the curve 32 corresponding, respectively, to the hot mode (R) and the cold mode (P), are symmetrical with respect to the point e of the curve 30 corresponding to the theoretical target power W c .
• the regeneration time is divided into a succession of fractional periods of operation, alternatively in hot mode (R) and in cold mode (P) in the manner represented at the bottom of the diagram by the crenellated line 33.
• the high plateau between the times t 1 and X 2 corresponds to a period in the hot mode during which the incoming power follows the curve 31 between the points ⁇ i and e 2 and the low plateau, between the instants X 2 and t 3 , corresponds to a period in cold mode during which the incoming power We follows the curve 32 between the points e ' 2 and e' 3 .
• the energy absorbed by the catalyst during a period corresponds to the integration, as a function of time, of the power provided by the gases.
• Line 34 indicates the variation in absolute value, during each fractional period, of this excess or energy deficiency with respect to the energy E theoretically necessary for maintaining the catalyst at a constant temperature T s .
• the curve T 1 indicates the variations in the temperature of the gases at the inlet of the catalyst 21 and the curve T 2 , the variations of the temperature at the outlet.
• the temperature T 2 of the gases also increases progressively at the outlet of the catalyst, with an offset due to the thermal inertia.
• the absorbed energy E 1 is greater than the required energy E and the difference increases progressively, as indicated by the line 34 in the diagram of FIG. 4, between the instants t 1 and X 2 A 1.
• this excess energy E 1 supplied by the gases reaches the maximum value E max and the engine is then switched to cold mode, following a low level of the line 33.
• This results in a failure of energy E 2 which is obtained by integration of the power failure D 2 and whose absolute value increases gradually to reach the same maximum value E max at time t 3 .
• the temperature T 1 at the inlet of the catalyst decreases and the result is, with delay, a decrease in the temperature T 2 at the outlet of the catalyst.
• each fractional period ti, X 2 in heating mode (R) or X 2 , X 3 in cooling mode (P) and so on is thus determined by controlling the change of combustion mode at the instant when the energy gap reached, by excess or by default, the limit value E max .
• the motor will thus be passed alternately from a so-called “hot mode” combustion mode, richer than what is necessary to obtain the desired power, to a poorer mode, called “ cold mode ", by controlling the duration of the split periods so that the surplus of energy brought in a period in” hot “mode is offset by the energy loss during the following period in” cold “mode, the passage of one mode to another being controlled when the surplus or the energy fault reaches a maximum value E max determined so as to limit the amplitude of variation of the temperature inside the monolith constituting the catalyst.
• the means for adjusting the combustion mode of the engine that is to say, essentially the fuel injection, can advantageously be controlled by a control unit of the type shown, by way of a preferred example, on Figure 5.
• the two combustion modes are first developed by establishing a map making it possible to estimate, at each instant, the exothermic reaction power W exo which in each of the two modes, the oxidizing and reducing masses reacting in the post-treatment organ will be provided.
• This exothermic power W exo is estimated by this potential exotherm 41 which applies a signal corresponding to an input of a block 4 for calculating the incoming power W 6 .
• This calculation block 4 receives, on the other hand, signals corresponding, respectively, to the temperature Te and to the flow rate Q eCh of the gases at the input of the monolith which can be measured by sensors 42, 43 or estimated according to engine speed. The energy potential of the motor adjustment is thus measured and estimated by the calculation block 4 by applying the equation indicated above:
• a calculation block 5 determines the desired power W c necessary to obtain this temperature Ts, from information displayed on its inputs 51, 52, 53 relating, respectively, to the temperature of the set point Ts, the flow rate Qec h gas measured or estimated upstream of the catalyst 21 and the energy loss W p in the catalyst that can be estimated or determined by modeling.
• the calculation block 5 thus determines the target power by applying the equation:
• the incoming power W 6 depends on the combustion mode, that is to say the exothermic reaction power W exo and can vary during the regeneration phase depending on the engine speed, the As indicated, for example, by the curves 31 and 32 of the diagram of FIG. 4, the setpoint power W c determined by the calculation block 5, varying in the same way by following the curve 30. From the variable values W 6 , W c thus determined by the calculation blocks
• the times of the split periods ti, X 2 in rich mode, X 2 X 3 in lean mode, t 3 1 4 in rich mode and so on, are determined by inverting the mode of combustion each time this excess E 1 or energy deficiency E 2 provided to the catalyst reaches, in absolute value, the fixed limit E max .
• This limit value E max is determined by a calculation block 6 by applying the equation:
• T max is a maximum temperature, displayed at the input of block 6, which must not be exceeded inside the post-processing unit,
• M is the total mass of the monolith constituting the catalyst
• E 1 or the energy fault E 2 determined by the calculation block 50 are displayed on a comparator 60 which, when the difference is zero, gives the means 1 1 fuel injection order to switch from a rich mode (R) to a lean mode (P) or vice versa.
• the temperature T 2 at the outlet of the catalyst 21 can be maintained in the vicinity of an average value which corresponds to the set temperature T s .
• the invention thus makes it possible, by controlling the injection of fuel into the engine, to maintain the temperature inside the catalyst at an optimum level as high as possible but remaining below a predetermined temperature T max .
• the invention is not limited, however, to the embodiment which has just been described as a simple example but encompasses all variants using equivalent means as well as other applications implementing similar means for the regeneration of post-processing systems.
• we will switch alternately from a rich mode to a poor mode but, in some cases, it could be interesting to manage the fractionation from two distinct poor modes, respectively hotter and colder, for example for the regeneration of soot in a post-treatment system of the type particulate filter or 4-way system placed downstream of a first DOC type system, NOx-Trap or 4-channels.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Exhaust Gas After Treatment (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

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• 2006
  • 2006-12-29 FR FR0656039A patent/FR2910928B1/fr not_active Expired - Fee Related
• 2007
  • 2007-12-21 US US12/521,638 patent/US8302381B2/en active Active
  • 2007-12-21 WO PCT/EP2007/064461 patent/WO2008083917A1/fr active Application Filing
  • 2007-12-21 JP JP2009543456A patent/JP2010514977A/ja active Pending
  • 2007-12-21 EP EP07858072.7A patent/EP2106498B1/de active Active

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